Index needle or hand for use with electrical measuring instruments.



B. WESTON. INDEX NEEDLE 0E HAND FOR USE WITH ELECTRICAL MEASURING INSTRUMENTS. APPLICATION FILED NOV. 9, 1909. 1 070 311) Patented Aug. 12,1913.

3 SHEETS-SHEET 1.

E. WESTON. INDEX NEEDLE 0R HAND FOR USE WITH ELECTRICAL MEASURING INSTRUMENTS.

APPLICATION FILED NOV. 9, 1909.

Patented Aug. 12, 1913.

3 SHEETSSHEET 2.

6] w-ve l IJIOZ NH-mm E. WESTON. INDEX NEEDLE 0R HAND FOR USE WITH ELECTRICAL MEASURING INSTRUMENTS.

APPLICATION FILED NOV.9,1909.

Patented Aug. 12, 1913.

3 SHBBT VSHEET s.

8 mm wtoz 23 51 QCfoznm I 4 accurately measuring electrical or EDWARD WESTON, or NEWARK, NEW JERSEY, assrenon 'r'o wnsroiv ELECTRICAL INSTRUMENT COMPANY. or WAVERLY ranx, new JERSEY, aconrona'rxon or NEW JERSEY.

INDEX NEEDLE OB HAND FOR USE WITH ELECTRICAL MEASURING INSTBUMENTS.

Specification of Letters ratent;

' Patented Aug. 12, 1913.,

Application filed November 9, 1909. Serial No. 527,098.

To all whom it may concern:

Be it known that I, EDWARD lVEs'roN, a subject of the King of Great Britain, and resident of Newark, county of Essex, and

5 State of New Jersey, have made a new and useful Invention in Index Needles or Hands for Use with Electrical Measuring Instruments, of whichthe following is a specifi cation. p

My invention, broadly speaking, relates to anew form of index needle or hand for use with electrical measuring instruments and is designed to overcome certain serious diificulties now and heretofore encouitlered in a etic quantities in those cases where the va no or direction of the forces are rapidly fluctuating or changing; such, for instance, as in the case of alternating currents. In measuring such forces we are confronted with the fact that in much practical and research work the rate of change of direction of the forces and also the magnitude of the changeare both likely to vary within extremely,

wide limits. To illustrate, the frequency (or rate of change of direction of the current) of alternating currents varies in practical work from about 15 cycles to 500. cycles per second, but in research work these limits are 39 frequently much extended. It is, therefore,

highly important to be able to make electrical or other measuring instruments intended for use on. alternating current circuits which will accurately indicate the value of the forces acting, no matter What the frequency may bewithin reasonable limits, and no matter how great the fluctuation in the values of those forces may be within rea sonable limits. 40' practically impossible, owing to the fact that alternating currents set up vibrations in the moving parts of the instrument which are transmitted to and set up more or less violent vibration of the pointer parts of index 7 hands, which vibration frequently becomes so eat as to make it impossible to determine its position with reference to the scale marking. It is true that these vibrations of the pointers of index hands of such instruments do not occur at all frequencies, but it is also invariably true that they do 'or may occur at several differentfrequencies in the same Heretofore this has been instrument, and at or about these frequen cies the instrument is practically worthless for the purpose for which it is intended.

My invention overcomes these difliculties and by its use I am able to make instru- 1 ments for use on alternating current circuits of all the widely varying frequencies within the limits of engineerin practice'in which the moving parts and in ex needles or hands carried thereby are entirely or practically entirely free from vibration and, therefore, the exact position of the pointer ti of the needle or hand over the scale can e accurately determined and the true value of the force or-forces acting be easily ascertained, no matter what the frequency may be or how violent or sudden-the change in value of the force or forces may be.

0 For a full and clear understanding of my lnvention, such as will enableothers skilled in-the art to construct and use the same,

reference is had to the accompanying drawings, in which, 1

Figure 1 is a plan view of the simplest form of my index needle or hand; and, Fig. 21s a side elevational view thereof, as seen looking at Fig. 1- from the bottomtoward the top of the drawing: Fig. 3 being an enlarged part sectional, part elevational detail view showing the'manner of connecting one of the members directlyto the fork or balance cross by which the needle or hand is connected to the stafi of the movable part of an electrical measuring instrument. Fig. 4 .1s a plan view of'a pointer tip especially adapted for use with. the needle or hand of apermanent or central station instrument. Flg. 5 is a perspective view of a modified form of the invention; and Fig. 6 isv a sectional view taken throu h Fig. 5 on the line XX and as seen loolring thereat in the direction of the. arrows. Fig. 7 is'a perspective view differing slightly in its structure from the form shown in Fig. 5; and Fig. 8 is a sectional view "taken through Fig. 7 on the line X-X andas seen looking thereat in-the direction of the arrows. and 10 illustrate conjointly plan views of a modified formof the invention in which the pointer part of the needle and the fork or balance cross are constructed of detachable .orseparable parts. Fig. 11 is a sectional Figs. 9

Ill!

"view talren through the body parts of Figs. 9 and it) and illustrating the manner of cori nesting the two parts of that form of the in vention shown in said figures to the staff of the movable part of the instrument, the pointer tip, however, not being shown in this view. Fig. 12 is a plan view of that form of the invention shown in Fig. 1, illustrating also further means of increasing the rigidity of the device through the agency of a counter-brace or member, the extreme ends of the other members which carry the pointer tip being broken away. Fig. 13 is a detail side elevational view of a part of F ig. l2 and as seen looking thereat from the bottom toward the top of the drawings. Fig. 14 is a plan view of a modified form of the invention somewhat similar to the form shown in Fig. 1, but having an especial adaptability for use in connection with por able instruments. Fig. 15 is a side elevational view of Fig. It as seen looking thereat from the bottom toward the top of the drawings.

Referring now to the drawings in detail and first to Figs. 1 to a inclusive, 1 represents the fort: or balance cross having at its center an elongated stafi opening 2 and provided with screw-threaded counter-balance or weight supporting arms 4;, 4, 4:, and two additional arms 3, 3, having substantially the angular relation to the fork or balance cross shown, this structural device being stamped, at one operation, out of light sheet metal, such as aluminum. 5, 5"represent angular members made preferably of finely drawn tubes of aluminum, to the outer interconnected ends of which is attached a pointer tip 5 also stamped out of thin sheet metal, as aluminum, and secured thereto by wrapping the hat lugs or cars at the inner end around such outer ends and then cementing the parts securely together. The arms 4i, i, are screw-threaded at their outer ends for the purpose of receiving the usual counter-weights. 'lhe arms 3, 3-, are bent so as to assume the angular relations in diller ent planes indicated in Figs. 1 and 2, and the outer ends thereof are then bent so as to coincide with the converging. angular relation of the tubular ends of thetwo members 5, 5. l hey are then coated'with cement and inserted. into these hollow ends, as shown in enlarged view Fig. 3, after which they are further permanently secured together by staking or indenting them with a prick punch. After the counter-weights are put 111 place the needle or hand as thus constructed is readyfor use. i

In Figs. 5, 5, 7 and 8 l have illustrated in perspective views further modified forms of the invention in whichin one instance there are three sets of conjoint members 5, 5, 5, and arms 3, 3, 3, secured to the fork or balance cross, which cross in the form shown in .that it has 5 embraces three members, the central one of which may, if preferred, be done away with, while in Fig. '2 this cross is similar to Fig. l insofar as the counterweight supporting arms is concerned. it will be observed that the construction of the forks shown in Figs. 5 and 7 are such that the members 5, 5, are located in did'erent planes, thus preventing, as far as possible, resonant vibration, in either a horizontal or a vertical direction, or in both directions. Figs. 6 and 8 illustrate the manner of connecting the pointer tip to the outer ends of the members 5, 5, 5.

In Figs, 9, 10 and 11 l have shown a still further modified form of the invention, in which the fork or balance cross 1 and the trussed parts proper are constructed in in dividual or separable parts, so that they may be joined together as a whole and secured to the stafi 2 of the movable part of the instrument. In this form of the invention the fork or balance cross is stamped out of a thin sheet of metal, as aluminum, and the'supporting part of the members 5, 5 and arms 3, 3 are stamped out of a second sheet of light metal, and the respective arms 3, 3, 4, a, given a cylindrical conformation or shape in any preferred manner, so that a minimum amount of metal is embodied in each instance and the arms 4, d, 4:, put in immediate condition for cutting the screwthreads'on the outer ends thereof, while the outer ends of the arms 3, 3, are also adapted to be quickly and easily inserted into the tubular ends of the members 5, 5. This form of the invention possesses especial merit in that the arms 4, lof the fork or balance cross, the arms 3, 3 of the supporting part for the members 5, 5, and these members themselves are all of cylindrical form and therefore possess minimum lightness and are of relatively great rigidity.

In Figs. 12 and 13 l have illustrated a form of the invention in which the structure is not essentially'diiferent from that shown in Figs. 1 and 2, except that a cross member 7 is provided which connects the two members 5, 5 together, said cross member being made of light sheet metal, such as aluminum and provided with longitudinal webs as shown, the opposite ends thereof being of sleeve like form and secured to the members 5, 5, as shown. This cross member is slipped into position over the ends of the members 5, 5, before such ends are secured to the arms 3, 3; or, it may be secured to the members by winding the extended ends of the member 7 about the joint ends of the members 5, 5, and arms 3, 3, after they are secured together in a manner similar to that in which the pointer tip 6 is secured to the outer ends of the same members. This form of the invention possesses especial utility in greater rigidity than the like Ill) structural form shown in Figs. 1 and 2 and prevents to a very great extent any torsional or twisting effects, thereby. constituting a structurewhich is not liable in any sense to be subject to resonant vibrations, such as will interfere with the reading at the end of the pointer tip. i

. Figs. 14 and 15 illustrate a form-of the invention substantially like that shown in Figs. 1 and 2, except that this form has an especial utility in connection with portable instruments, the only essential difference between the device shown in Figs. 14 and 15 and that shown in Figs. 1 and 2 being that the two members 5, 5 insaid Figs. 14 and 15 are formed from one continuous piece of tubing bent at its middle back upon itself so as to have -'the acute angular relation shown in Fig. 14, and after being so bent cement is applied to the adjoining surfaces and the pointer tip 6 is formed by fiatt ening the same through the agencv of a pair of pliers, or in any preferred way, thus producing a thin narrow pointer tip. A pointer and pointer tip for an index needle or hand as thus constructed, in which the two members 5, 5 are integrally connected with the tip, gives increased rigidity at the outer end and, therefore, practically prevents resonant vibrations, such as will interfere with the reading at the end of the pointer tip.

I do not limit my invention to the details of construction illustrated in the accompanying drawings, as obviously various modifications will suggest themselves to those skilled in the art which would embody the essential feature of preventing resonant vibrations of such pointers by utilizing the truss or rigid effects of variously disposed members and interrelated cross members. To illustrate, the entire index needle or hand might be "onstructed by stamping it out as a whole from a relatively thin sheet of light metal,

such as aluminum, so that all of the parts thereof, including the fork or balance cross 1 the counter-weight arms A, 4, 4, the members 5, 5, of the pointer proper, the supporting arms 3 3, therefor, and the pointer tip 6, are embraced in one integral piece and the members 3, 3, of such needle might be afterward bent into the conformation shown in Fig. 2; or all of the parts of such needle might be located in a common plane. It is also obvious that the form shown in Figs. 9, 10 and 11 might be constructed in this manner of two parts in which the arms 3, 3, members 5, 5 and pointer tip 6 would be in one integral piece and the'forkor balance cross 1 and arms 4, 4,4 in an independent integral piece, all such modifications falling within the generic scope of my invention.

It will thus be seen that in all the forms I have provided. a hand or pointer made up of a plurality of longitudinally disposed diverging and converging members comprising the parts 3 and 5, to form a sort of trussed structure.

It will further be readily understood that when a disturbing vibration or resonant effect acting in the plane or planes of said *members, tends to move the pointer tip in either direction, said members will be subjected to longitudinal stresses or strains in opposite directions, but owing to the stiffness of the structure, the metal of said members will not be appreciably distorted by these stresses or strains, and no appreciable energy will be stored up; consequently, no reacting spring-like vibrations result from said forces, and therefore a non-vibratory needle of a minimum weight, moment of inertia and momentum for a given rigidity results.

I make no claim hereinafter to the modified form shown in Figs. 14 and 15 of the drawings, as this constitutes the subject matter of a divisional application bearing Serial No. 752,568, filed by me on the 7th day of March, .1913.

Having thus described my invention what I claim and desire to secure by Letters Patent of the United States is:

1. A non-vibrating index needle or hand for electrical measuring instruments comprising a plurality of diverging and converging members separated from and rigidly secured at an angle to each other.

2. A non-vibrating index needle or hand for electrical measuring instruments comprisin a fork or balance member and a plurality of converging and diverging mem bers rigidly secured to said balance member and to each other.

3. An index needle or hand for electrical measuring instruments comprising a pinrality of converging and diverging mem ers separated from and rigidly secured at an angle toeach other; a pointer tip associated with said members; and a fork or balance 'cross also associated with said members.

4. An index needle or hand for electrical measuring instruments comprising a plurality of converging and diverging members separated from and rigidly secured at. an angle to each other; a counter-weight arm associated with said members; and means adapted to be connected with the instrument for moving said members and counterweight arm.

5. An index needle or hand'for electrical measuring instruments comprising a plurality of diverging members rigidly secured at an angle to each other; a pointer tip associated with said members; and a common support for said members.

6. An index needle or hand for electrical measuring instruments comprising a plurality of bent members separated from and rigidly secured at an angle to each other; a pointer tip associated with said members;

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